I’m getting bubbling in my reservoir tank but it’s not overheating and not smoking…also seems to be running fine. Is it a blown head gasket or something else? 2010 F-150 5.4

 

If nobody did any work with the cooling system and it could be getting rid of trapped air, might be a good idea to have a a pressure test done.
Questionable water pump seal could be pulling in air and sending it out the recovery bottle.

How does the coolant level look ?

 

We thought maybe it was the oil filter adapter because the old reservoir had been blackened on the inside top and the radiator was gunky. We replaced the adapter, flushed both the engine and radiator, replaced radiator hoses and reservoir tank. Then noticed droplets on the inside top of the new reservoir. Seems to be running fine though with no blue smoke and no overheating. May have lost a little coolant since though. No milky oil either. I’ve been quoted 6,000 to replace both gaskets and timing chain. Truck only has 140,000 on it.

 

Would a coolant chemical check be my next move? Then maybe a compression check? I had a mechanic tell me if it’s running fine then it has compression. I’m confused as hell.